are php brief tags tolerable use?

here's information :

there 4 opposite pairs of
opening shutting tags be
used php. twin those, <?php ?>
<script language="php"> </script>,
always available. two
brief tags asp impression tags, and
incited off the
php.ini settlement file. such,
while brief tags and
asp impression tags convenient, are
reduction portable, generally not
recommended.

in trust many servers do have brief tags enabled. typing

<?=

is distant some-more accessible typing

<?php relate 

the programmers preference an vicious factor, why recommended?